There has been a demand for a silver halide light-sensitive material particularly for shooting which achieves high sensitivity, such as ISO 400 sensitivity (Super HG-400), while exhibiting excellent image quality, including graininess, sharpness and color reproducibility, equal to that of light-sensitive materials having ISO sensitivity 100.
As a means for improving graininess, silver halide grains having a distinct stratiform structure containing from 7 to 45 mol % of silver iodide and having an average silver iodide content of at least 7 mol % have been proposed as disclosed in JP-A-60-143331 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). Since a mere use of such silver halide grains still leaves problems of sharpness and color reproducibility, it has been recently proposed to use these emulsion grains in combination with a so-called DIR coupler capable of imagewise releasing a development inhibitor as disclosed in JP-A-1-186938, JP-A-1-259359, JP-A-1-269935, and JP-A-2-28637. These techniques brought about some improvements in graininess, sharpness, and color reproducibility, but the reached level was still unsatisfactory. In addition, when light-sensitive materials having the above-described means are processed in a usual manner currently spread in photofinishing laboratories, i.e., continuously processed while supplying a developing solution for replenishment, it turned out that a developing solution gradually comes to have decreased or increased activity.
On the other hand, hydrolyzable DIR couplers or compounds which improve sharpness as well as color reproducibility while causing no change in activity of a developing solution have been proposed as described in JP-A-57-151944, JP-A-58-205150, JP-A-1-280755, and U.S. Pat. No. 4,782,012. These DIR couplers or compounds are capable of releasing a development inhibitor moiety which undergoes hydrolysis in a developing solution to lose its inhibitory activity. While variations of activity of a developing solution were somewhat suppressed by using these compounds, the produced effects were still insufficient. In particular, when those capable of releasing a development inhibitor which releases an aryloxy ion or an arylamine ion when inactivated in a developing solution are used, it was found that the released aryloxy ion or an arylamine ion is incorporated into oil droplets of couplers of a light-sensitive material, causing variations in coupling activity of compounds. Further, so-called timing type DIR couplers need improvements in stability and cost for synthesis. Furthermore, DIR couplers which release a development inhibitor via a sulfur atom thereof as described in U.S. Pat. No. 4,782,012 have low coupling activity, i.e., low rate of development inhibitor release so that sufficient improved effects on color reproducibility and sharpness can not be obtained.